package LuoGu.递归_递推.数的计算;

import java.util.Scanner;

public class Main_fail {
    static int ans = 1;
    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        int n = s.nextInt();
        dfs(n);
        System.out.print(ans);
    }
    public static void dfs(int n){
        for(int i=1;i<=n/2;i++){
            dfs(i);
            ans++;
        }
    }
}
